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  • Handling missing data

    - by soppotare
    Say I have a simple helpdesk application which logs calls made by users. I would typically have such fields in a table relating to the call e.g. CallID, Description, CustomerID etc. I Would also have a table of customers including CustomerID, Username, Password, FullName etc. Now when a user is deleted from the customers table then the inner join between the calls table and the users table to find out historically which user logged a call would produce no results. How do people usually deal with this? Have seperate customer and useraccount tables Just disable the accounts so the data is still available Record the customers name in the calls table as a seperate field. or any other methods / suggestions?

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  • Constructors + Dependency Injection

    - by Sunny
    If I am writing up a class with more than 1 constructor parameter like: class A{ public A(Dependency1 d1, Dependency2 d2, ...){} } I usually create a "argument holder"-type of class like: class AArgs{ public Dependency1 d1 { get; private set; } public Dependency2 d2 { get; private set; } ... } and then: class A{ public A(AArgs args){} } Typically, using a DI-container I can configure the constructor for dependencies & resolve them & so there is minimum impact when the constructors need to change. Is this considered an anti-pattern and/or any arguments against doing this?

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  • Should Service Depend on Many Repositories, or Break Them Up?

    - by Josh Pollard
    I'm using a repository pattern for my data access. So I basically have a repository per table/class. My UI currently uses service classes to actually get things done, and these service classes wrap, and therefore depend on repositories. In many cases my services are only dependent upon one or two repositories, so things aren't too crazy. Unfortunately, one of my forms in the UI expects the user to enter data that will span five different tables. For this form I made a single service class that depends upon five repositories. Then the methods within the service for saving and loading the data call the appropriate methods on all of the corresponding repositories. As you can imagine, the save and load methods in this service are really big. Also, unit testing this service is getting really difficult because I have to setup so many fake repositories. Would it have been a better choice to break this single service apart into a few smaller services? It would put more code at the UI layer, but would make the services smaller and more testable.

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  • Interpreted languages: The higher-level the faster?

    - by immersion
    I have designed around 5 experimental languages and interpreters for them so far, for education, as a hobby and for fun. One thing I noticed: The assembly-like language featuring only subroutines and conditional jumps as structures was much slower than the high-level language featuring if, while and so on. I developed them both simultaneously and both were interpreted languages. I wrote the interpreters in C++ and I tried to optimize the code-execution part to be as fast as possible. My hypothesis: In almost all cases, performance of interpreted languages rises with their level (high/low). Am I basically right with this? (If not, why?)

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  • fast load big object graph from DB

    - by Famos
    Hi I have my own data structure written in C# like: public class ElectricScheme { public List<Element> Elements { get; set; } public List<Net> Nets { get; set; } } public class Element { public string IdName { get; set; } public string Func { get; set; } public string Name { get; set; } public BaseElementType Type { get; set; } public List<Pin> Pins { get; set; } } public class Pin { public string IdName { get; set; } public string Name { get; set; } public BasePinType PinType { get; set; } public BasePinDirection PinDirection { get; set; } } public class Net { public string IdName { get; set; } public string Name { get; set; } public List<Tuple<Element,Pin>> ConnectionPoints { get; set; } } Where Elements count ~19000, each element contain =3 Pin, Nets count ~20000, each net contain =3 pair (Element, Pin) Parse txt (file size ~17mb) file takes 5 minutes. Serilization / Deserialization by default serializer ~3 minutes. Load from DB 20 minutes and not loaded... I use Entity Framework like public ElectricScheme LoadScheme(int schemeId) { var eScheme = (from s in container.ElectricSchemesSet where s.IdElectricScheme.Equals(schemeId) select s).FirstOrDefault(); if (eScheme == null) return null; container.LoadProperty(eScheme, "Elements"); container.LoadProperty(eScheme, "Nets"); container.LoadProperty(eScheme, "Elements.Pins"); return eScheme; } The problem is dependencies between Element and Pin... (for ~19000 elements ~95000 pins) Any ideas?

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  • Good JDBC pattern

    - by Java Developer
    What is the good practice for database operation in Java application? Do you construct the DML syntax in the Java code and send the statements to DB engine for execution, or you just collect the parameters and then make a call to stored procedure with the parameters via java code? or neither because that's just not how to do it? can anyone give an example of a full database utility classes to do database operations in Java app? also what about the transaction manager? My assignment is to make database operation that is modular in Java. Thanks

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  • Singletons and constants

    - by devoured elysium
    I am making a program which makes use of a couple of constants. At first, each time I needed to use a constant, I'd define it as //C# private static readonly int MyConstant = xxx; //Java private static final int MyConstant = xxx; in the class where I'd need it. After some time, I started to realise that some constants would be needed in more than one class. At this time, I had 3 choises: To define them in the different classes that needed it. This leads to repetition. If by some reason later I need to change one of them, I'd have to check in all classes to replace them everywhere. To define a static class/singleton with all the constants as public. If I needed a constant X in ClassA, ClassB and ClassC, I could just define it in ClassA as public, and then have ClassB and ClassC refer to them. This solution doesn't seem that good to me as it introduces even more dependencies as the classes already have between them. I ended up implementing my code with the second option. Is that the best alternative? I feel I am probably missing some other better alternative. What worries me about using the singleton here is that it is nowhere clear to a user of the class that this class is using the singleton. Maybe I could create a ConstantsClass that held all the constants needed and then I'd pass it in the constructor to the classes that'd need it? Thanks

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  • In java web application, where should i store users photos?

    - by stunaz
    Hello, this questions may be stupid, but i dont really see how to resolve it : lest say that in my application, i have a user. This user edit his profile, and need to edit his avatar. Where should i store the avatar file? first of all i was saving all the files in src\main\webapp\resources , but each time i redeploy that folder empties. so i dedide to place in an other location : c:\wwwdir\resources, but i can't link local resources from remote pages, so i was not able to display any avatar . any idea? advise? link?

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  • Do Java or C++ lack any OO features?

    - by tsv
    I am interested in understanding object-oriented programming in a more academic and abstract way than I currently do, and want to know if there are any object-oriented concepts Java and C++ fail to implement. I realise neither of the languages are "pure" OO, but I am interested in what (if anything) they lack, not what they have extra.

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  • An issue on object orientation in php

    - by rabidmachine9
    Hello people, I have come up to issues while I'm trying to write some classes, here is an example: I have this class called TwitterGrub and I cant call it like that: $c = new TwitterGrub(); $c->twitterDisplay(); here is the class itself: <?php class TwitterGrub{ function twitterCapture($user = 'username',$password = 'pass') { $ch = curl_init("https://twitter.com/statuses/user_timeline.xml"); curl_setopt($ch, CURLOPT_HEADER, 1); curl_setopt($ch,CURLOPT_TIMEOUT, 30); curl_setopt($ch,CURLOPT_USERPWD,$user . ":" . $password); curl_setopt($ch,CURLOPT_RETURNTRANSFER,1); curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, 0); curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 0); $result=curl_exec ($ch); $data = strstr($result, '<?'); $xml = new SimpleXMLElement($data); return $xml; } function twitterDisplay($twitNum = 2){ $xml = $this::twitterCapture(); for($i= 0; $i<$twitNum; $i++){ echo "<div class= 'curvebox'>".$xml->status[$i]->text."</div>"; } } } ?> The problem is that everytime I want to change the username or password I have to jump back to class definition and that makes things not modular... and in many ways it feels wrong. So the question is what would be the proper way to chance my username and password through the objects interface and then call twitterDisplay() method with the new data?Hope that makes sense. Thanks in advance

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  • How to dispose the objects created by factory pattern

    - by Ram
    Hi, I am using Factory pattern to create .NET objects of a class. I also need to make sure that all such objects should be disposed before application terminates. Where and How can I dispose the objects created by factory pattern? Shall I dispose in the class in which I am getting the objects created by factory?

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  • C++ OOP: Which functions to put into the class?

    - by oh boy
    Assume I have a class a: class a { public: void load_data( ); private: void check_data( ); void work_data( ); void analyze_data( ); } Those functions all do something with the class or one of its members. However this function: bool validate_something( myType myData ) { if ( myData.blah > 0 && myData.blah < 100 ) { return true; } return false; } Is related to the class and will only be called by it, so it won't be needed anywhere else Doesn't do anything with the class or its members - just a small "utility" function Where to put validate_something? Inside or outside the class?

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  • Adding interfaces that won't be actually used

    - by devoured elysium
    I currently have two interfaces(that I'll name here IA and IB): interface IA { int Width; int Height; ... } interface IB { int Width; int Height; ... } that share the same two properties: they both have a Width and a Height property. I was thinking if there is any point in defining an IMatrix interface containing a Width and Height properties: interface IMatrix { int Width; int Height; } The thing is that although they share both the same properties, I won't make use of polymorphism with IMatrix in any of my coding: i.e., there won't by any situation where I'll want to use an IMatrix, I'll just want to use IA and IB. Adding an IMatrix seems more like over-engineering than other thing, but I'd like to ask you guys what your opinion is on the matter. Thanks

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  • What exactly is GRASP's Controller about?

    - by devoured elysium
    What is the idea behind Grasp's Controller pattern? My current interpretation is that sometimes you want to achieve something that needs to use a couple of classes but none of those classes could or has access to the information needed to do it, so you create a new class that does the job, having references to all the needed classes(this is, could be the information expert). Is this a correct view of what Grasp's Controller is about? Generally when googling or SO'ing controller, I just get results about MVC's (and whatnot) which are topics that I don't understand about, so I'd like answers that don't assume I know ASP.NET's MVC or something :( Thanks

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